1. Field of the Invention
The present invention generally relates to access data networks that use at least one shared access communication channel to communicate between a plurality of nodes in the network and a terminal to which the plurality of nodes is connected. More specifically, the present invention provides methods and devices for detecting and/or preventing use of forged configuration files relating to cable modem networks.
2. Description of Related Art
Broadband access technologies such as cable, fiber optic, and wireless have made rapid progress in recent years. There has been a convergence of voice and data networks, which is due in part to the deregulation of the telecommunications industry in the United States. In order to stay competitive, companies offering broadband access technologies need to support voice, video, and other high-bandwidth applications over their local access networks. For networks that use a shared access medium to communicate between subscribers and the service provider (e.g., cable networks, wireless networks, etc.), providing reliable high-quality voice/video communication over such networks is not an easy task.
One type of broadband access technology relates to cable modem networks. A cable modem network or “cable plant” employs cable modems, which are an improvement of conventional PC data modems and provide high speed connectivity. Cable modems are therefore instrumental in transforming the cable system into a full service provider of video, voice and data telecommunications services.
Cable service providers need to make different levels of service available to customers, typically with corresponding differences in price. For example, some customers may need relatively higher data transfer rates than others and are willing to pay a premium for a higher quality of service that can provide such transfer rates. Other customers may be content with a slower and less expensive service. Typically, the same type of cable modem is used by customers having a higher quality of service and customers having a lower quality of service. The cable service provider distinguishes between such customers based on configuration files assigned to different classes of customers.
Some customers have developed theft of service techniques for obtaining a higher quality of service than the service for which these customers have paid. Some such techniques take advantage of defects in the way a number of different vendor's cable modem products perform the Trivial File Transfer Protocol (TFTP) provisioning process. Some such defects allow end users to “fool” their cable modems into downloading a forged Data-over-Cable Service Interface Specifications (DOCSIS) configuration file from a local TFTP server rather than from the cable service provider's legitimate TFTP server, hence granting the thief a potentially higher level of service than that to which they are entitled. It would be very useful to be able to detect and/or prevent such theft of service.